It is well known that the printing inks utilized today are modified with various types of rheological additives to provide required rheological properties to ensure quality printing on high speed printing presses. Generally, polymer (or resin), solvent and pigment types determine the intrinsic rheology of the ink formulation. Ideally, the formulators hope to achieve all the rheological properties from the resin system they choose. However, to fine tune the rheology and improve overall performance properties of their inks, formulators most often seek “rheological additives.” The rheological modifiers are one of the most important additives utilized in printing ink formulations. The additives are utilized to modify the rheological properties of printing inks to meet the requirements of various types of printing presses. It has been long known that organoclays have been used to control rheology and reduce ink misting on high speed presses. The assignee hereof has long offered a line of products sold under the trademark BENTONE® to ink manufacturers.
It has been long known, since at least the 1950s, that organoclays (also called organophilic clays) can be used to thicken ink systems. See the very early article by an employee of the assignee hereof J. W. Jordan, “Proceedings of the 10th National Conference on Clays and Clay Minerals” (1963), which discusses a range of applications of organoclays from high polarity liquids to low polarity liquids. See also U.S. Pat. No. 4,475,950.
U.S. Pat. Nos. 5,735,943; 5,718,841 and 5,429,999 describe the use of organoclays in various applications.
Organoclays are manufactured as dry powders and require significant processing on the part of the ink formulator/manufacturer to fully disperse and activate them into ink formulations. The dry powders are often very difficult to disperse in inks because of the need for high shear mixing equipment, increased temperatures and longer mixing conditions. In addition, the powdered materials require additional man-power to handle the bags to charge them into the ink mixing kettle which creates unhealthy dust conditions.
Ink manufacturers have long sought an easy to add, pumpable or pourable rheological additive which can be incorporated without handling dusty powders and requiring lengthy processing requirements. A liquid rheological additive would also be beneficial as a post additive to fine tune the viscosity of finished inks. There is clearly a need for a liquid rheological additive which can be utilized in an offset ink making process. The use of liquid rheological additive would allow the ink manufacturers to streamline the manufacturing process. As the ink manufacturing process changes toward faster throughput and full automation, the ink manufacturers demand easy to disperse, pumpable raw materials in their formulations so that lengthy processing and milling are eliminated.
Patents of the prior art that show developments related to the chemistry of additives useful in various fields, other than organoclays, include the following:
U.S. Patent Application Publication No. 2001/0009890 shows an invert emulsion suitable for drilling a subterranean well which uses an ester of a C1 to C12 alcohol and a C8 to C24 monocarboxylic acid; Ethomeen C/15 can be used as an agent in the invention described in the application.
U.S. Pat. No. 5,536,871 also issued to the assignee hereof describes a rheological additive which comprises the reaction product of a polyalkoxylated nitrogen-containing compound such as polyoxyethylene (5) cocoalkylamine, a polycarboxylic acid including dimer acids and a liquid diamine.
U.S. patent application Ser. No. 10/303,037, filed by assignee hereto, describes an additive that provides flat rheology to oil well drilling fluids, particularly those used in deep water drilling comprised of a reaction product of a carboxylic acid with at least two carboxylic acid moieties and a polyamine having an amine functionality of two or more.
U.S. Pat. No. 5,610,110 also issued to assignee hereof shows an improved drilling fluid containing a reaction product of an alkoxylated aliphatic amino compound and an organic polycarboxylic acid and a clay based organoclay.